A number of cartridges have been developed which employ a continuous tape loop for magnetic tape recorders since such cartridges offer a number of unique features, such as immediate reply without rewinding or reversing the cartridge. Typical examples of the endless loop type cartridge are shown in U.S. Pats. Nos. 2,778,635; 2,778,636, and 2,778,637 issued to Eash and U.S. Pat. No. 2,426,838 issued to Miller.
When employing the endless loop tape cartridges referred to in the above patents, special recorders are required to meet the necesssary drive system for tape transport as well as other specifications to insure positive tape feed without wow and flutter. While the above specialized tape cartridge will function properly in their tailor made recorders, they are not suitable for use in the commercially marketed "Cassette Recorder" which are all designed to use a reel-to-reel type cartridge of a standard size and design. These recorders are manufactured and sold commercially by a number of different companies and their standardized reel-to-reel cassette cartridges are loaded with varying amounts of magnetic tape. Commonly, these cassette cartridges have from 30 to 60 minutes of tape load the cartridges are reversed in the cassette recorder to employ both halves (tracks) of the magnetic tape thereby doubling their effective tape load in minutes.
While the reversal of these cassette cartridges within the recorder will rewind the other half or track of the tape as a track is utilized, reversing the cartridges in the recorder is difficult to accomplish automatically. Further, in many of the applications where cassette recorders are employed, a number of sophisticated switching techniques are required to reverse the tape transport to rewind the tape and to sense the end of the tape transport as the last convolution leaves a reel.
One of the features which has made the cassette recorder such a widely purchased machine is its compactness and convenience of the recorder and the tape cartridges. As a result, its compactness requires that the capstan drive be quite small (a diameter of approximately 0.079 inch) and therefore the surface area of the tape on which the capstan operates to drive the tape is quite limited. In order to insure positive speed, these types of recorders employ a forward drive reel which is clutched in the cassette drive system and drives the take-up reel to help the capstan achieve smooth uniform tape transport to avoid wow and flutter in the recording being made on or reproduced from the tape. Since normally the power required for tape transport is greater in an endless loop tape arrangement than reel-to-reel arrangements satisfactory endless loop cartridges have not been available for cassette recorders.
An object of the present invention is to provide a satisfactory continuous loop cassette cartridge for the currently commerically available cassette recorders, which will require no modification to the recorder to employ the novel cartridge.
A further object of the invention is to provide a cassette cartridge with an endless loop contained therein which is compatible with the cassette recording machines currently marketed in the United States.
It is also an object of the present invention to provide an endless loop cassette cartridge of substantially the same size and outward appearance as convention reel-to-reel cassette cartridges so that the endless loop cassette cartridge will be compatible with various automatic changing mechanisms for cassette cartridges.
An ancillary object of the invention is to provide an endless loop cassette cartridge with internal switching devices whereby positive tape indexing can be achieved through conductive patches on the endless tape loop which will close contacts within the novel cartridge thereby making the novel cartridge even more suitable for a number of applications.
A further object of the present invention is to provide a reliable and economical endless loop cassette cartridge for conventional cassette recorders which is serviceable and troublefree in operation.
A number of other objects and advantages will be apparent from the following description of the present invention.